There is known the device that comprises an outer member of cylindrical shape, an inner member of cylindrical shape arranged inside the outer member, and an elastic member connecting these outer and inner cylindrical members, wherein a spring constant in the axial direction of the inner member is heightened (see a patent reference 1).
FIG. 12 is a cross sectional view schematically showing an engine mount (a vibration isolating device) disclosed in the above patent reference 1. This engine mount has an inner member 130 which is concentrically arranged inside of a cylindrical member 112 provided in an outer member and an elastic member 120 which provides a connection between the outer member 112 and the inner member 130. The inner member 130 of a shaft shaped member is carried in an axially movable manner with respect to the outer member 112 (in the following description, the axial direction of the inner member 130 shall be referred to as a Y direction).
Further, a downwardly projecting inner member side projection 133 is provided in an end portion in the Y direction of the inner member 130. A projection 115 which projects downwardly in the drawing is provided on an opening side located on an end of the cylindrical member 112 so as to be opposed to the inner member side projection 133. The inner member side projection 133 and the projection 115 are connected to each other by a Y direction elastic part 124 which is a continuous portion of the elastic body 120. The Y direction elastic part 124 is a part to be elastically deformed mainly by movement in the Y direction of the inner member 130.
This engine mount supports an engine in a vibration isolating manner by mounting the outer member 112 on a vehicle body 142 and mounting the inner member 130 on the engine (not shown).
In addition, when the inner member 130 is moved to the left side in the Y direction of the drawing due to a vibration of the engine, the Y direction elastic part 124 is compressed and deformed between the inner member side projection 133 and the projection 115. Therefore, the spring constant in the Y direction of the elastic body 120 becomes higher.